Takumi is a high school student. He is withdrawn and is not interested in 3D things. In his town, a mysterious serial murder case happens and people get panicked. One day, when he chats on the internet, a man suddenly contacts him and gives him an URL. He goes to the website and finds a blog image that suggests a next murder case.... On the next day, it really happens....
Takumi suffers from intense delusions as a result of his apparent schizophrenia and the extremely secluded lifestyle he lives as a hikkikomori. One day he accidentally stumbles upon a gruesome murder scene, a part of a chain of events called "New Generation." After this, his life gets caught up in these events, and he meets a bunch of increasingly insane anime girls with swords.

As you can tell, I love the way they told this story. If they had a 20 in this section, I would give it. Now, I will tell my reasons.

You already know that this was a great thriller, as it keeps one guessing right up until the end. And your interpretations of the characters change on a pretty constant basis as the story progresses. Here's an example: I first hated Takumi, but at the end of the series, one could only feel jealous of the ------- with a certifiable harem of great women and the powers of a god. Perhaps this is all a little exagerated, but I think my point was made rather readily with that.

Thriller anime are either great or they suck. This was one of the great ones that came with a few bonuses, including some pretty good backstory and backworkings within the story.